Acquired Peripheral Nerve Injury Findings in Critically Ill COVID-19 Patients

We retrospectively analyzed clinical, NCS/EMG, and NMRI aspects of five COVID-19 intensive care unit inpatients that received mechanical ventilation. After awakening from sedation, they experienced peripheral neuromyopathic symptoms. Teaching Point: Acquired peripheral nerve injury has been described in COVID-19 infection and knowledge of the clinical, nerve conduction studies/electromyography (NCS/EMG) and neurographic magnetic resonance imaging (NMRI) findings are crucial.


CASE HISTORY 1
A 48-year-old woman presented with sudden onset of severe burning pain and progressive weakness in the left shoulder girdle. NCS/EMG suggested acute motor sensory axonal neuropathy (AMSAN) and left brachial neuritis. Left brachial plexus NMRI was consistent with Parsonage-Turner syndrome ( Figure 1B and 1C).

CASE HISTORY 2
A 69-year-old man presented with flaccid quadriplegia, upper limbs areflexia and lower limbs hyporeflexia. NCS/EMG suggested a sensorimotor polyneuropathy (attributed to critical illness polyneuropathy) and Parsonage-Turner syndrome, confirmed by NMRI.

CASE HISTORY 3
A 78-year-old woman presented with prone positioning for two days. Quadriplegia due to critical illness polyneuropathy and left shoulder pain was present after awakening from sedation. NCS/EMG and NMRI were consistent with Parsonage-Turner syndrome ( Figure 1A).

CASE HISTORY 4
A 35-year-old woman presented with anesthesia and distal left leg muscle strength grade 0. Lumbosacral plexus MRI revealed signs of sciatic neuritis (Figure 2). Mononeuropathy related to COVID-19 was diagnosed.

CASE HISTORY 5
A 48-year-old woman presented with numbness along the fifth and fourth left fingers, weakness and volume  loss between first and second metacarpal bones. Elbow MRI was consistent with ulnar neuropathy (Figure 3), attributed to ulnar nerve compression lesion.
Post-infectious inflammatory peripheral nerve injury is thought to be immune-mediated and occurs in the setting of several viruses [1]. Peripheral nerve injury has been described following the use of prone positioning for COVID-19-related acute respiratory distress syndrome [1,[5][6][7][8] and brachial plexus is at greater risk [5,9], as a result of traction during decubitus changes and stretch/ compression injury from prolonged prone positioning [1,9]. Positioning-related peripheral nerve injury typically results in neuropraxia or axonotmesis [1,6]. Corresponding NMRI findings include nerve signal hyperintensity, thickening, and sometimes, fascicular enlargement. Polyneuropathy and critical illness myopathy are wellknown complications of critical care treatment [10]. COVID-19 patients may have critical illness myopathy superimposed with peripheral nerve injury. MRI may show a pattern of muscle edema correlated with expected distribution of innervation of the affected peripheral nerve [1].

CONCLUSIONS
Clinical, NCS/EMG, and NMRI are important to assess the potential etiologies and severity of peripheral nerve injury. Early diagnosis may guide treatment decisions, which could improve the clinical outcome.

FUNDING INFORMATION
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

COMPETING INTERESTS
The authors have no competing interests to declare.  Coronal T1WI (A) and corresponding coronal T2WI (B) with fat suppression show ulnar nerve thickening and T2WI increased signal intensity at the level and distal to cubital tunnel (red arrows), suggesting ulnar neuropathy. Axial T2WI with fat suppression (C) depicts ulnar nerve thickening and increased signal intensity (red arrow), also as high signal intensity in the flexor carpi ulnaris (yellow arrow) and flexor digitorum profundus (blue arrow) due to edema/denervation. R = radius; U = ulna.